Fraunhofer-Institut für Atmosphärische Umweltforschung IFU

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  • Publication
    Interactive effects of ozone and low UV-B radiation on antioxidants in spruce (Picea abies) and pine (Pinus sylvestris) needles
    ( 1998)
    Baumbusch, L.O.
    ;
    Eiblmeier, M.
    ;
    Schnitzler, J.-P.
    ;
    Heller, W.
    ;
    Sandermann, H.
    ;
    Polle, A.
    To study the role of low UV-B radiation in modulating the response of antioxidants to ozone. 4-year-old pine (Pinus sylrestris L.) and spruce (Picea abies L.) seedlings potted in natural soil, were exposed in phytochambers to fluctuating ozone concentrations between 9 and 113 nl l(-1) according to held data recorded at Mt Wank ( 1175 m above sea level. Bavaria, Germany) and two-times ambient O3 levels. UV-B radiation was either added at a biologically effective level of ca 1.2 kJ m(-2) day(-1) which is close to that found in March at Mt Wank, or was excluded by filters ( <0.08 kJ m(-2) day(-1)). After one growth phase current-year needles were collected and analysed for antioxidative enzyme activities (superoxide dismutase. SOD. EC 1. 15. 1. 1: catalase, CAT, EC 1. 11. 1.6: guaiacol peroxidase. POD. EC 1. 11. 1.7) and soluble antioxidants (ascorbatc glutathione). CAT. POD, ascorbate and clutathicme, but not SOD, were increased in needles of both species in response to twice ambient O3 levels. UV-B radiation in the presence of ambient O3 caused an increase in total SOD activity in spruce but had no effects on antioxidants in pine. Twice ambient O3 levels together with low UV-B radiation counteracted the O3-induced increases in ascorbate and CAT in pine but not in spruce. Under these conditions spruce needles showed the highest antioxidative protection and revealed no indication of lipid peroxidation. Pine needles exposed to UV-B and elevated O3 levels showed elevated lipid peroxidation and a 5-fold increase in dehydroascorbate, suggesting that this species was less protected and suffered higher oxidative stress than spruce.
  • Publication
    Black alder (Alnus Glutinosa (L.) Gaertn.) trees mediate methane and nitrous oxide emission from the soil to the atmosphere
    ( 1998)
    Rusch, H.
    ;
    Rennenberg, H.
    Three-year-old seedlings of black alder (Alnus glutinosa (L) Gaertn.), a common European wetland tree species, were grown in native soil taken from an alder swamp. Fluxes of methane (CH4) and nitrous oxide (N2O) between the tree stem and the atmosphere were determined under controlled conditions. Both CH4 and N2O were emitted through the bark of the stem into the atmosphere when the root zone exhibited 'higher-than-ambient' CH4 and N2O gas mixing ratios. Flooding of the soil caused a decreased N2O emission but an increased CH4 efflux from the stem. Immediately after flooding of the soil, N2O was emitted from the seedlings' bark at a rate of 350 my mol N2O m(-2) h(-1) whereas CH4 flux could not be detected. After more than 40 days of flooding CH4 fluxes up to 3750 my mol CH4 m(-2) h(-1) from the stem were measured, while N2O emission had decreased below the limit of detection. Gas efflux decreased with increasing stem height and correlated with gas mixing ratios in the soil, indicating diffusion through the aerenchyma as the major path of gas transport. From these results it is assumed that woody species with aerenchyma can serve as conduits for soil-derived trace gases into the atmosphere, to date only shown for herbaceous plants. This, yet unidentified, 'woody plant pathway' contributes to the total greenhouse gas source strength of wetlands.
  • Publication
    A most probable number method (MPN) for the estimation of cell numbers of heterotrophic nitrifying bacteria in soil
    ( 1998)
    Papen, H.
    ;
    Berg, R. von
    A Most Probable Number (MPN) method was developed allowing for the first time estimation of populations of bacteria capable of heterotrophic nitrification. The method was applied to an acidic soil of a coniferous forest exhibiting nitrate production. In this soil nitrate production was unlikely to be catalyzed by autotrophic nitrifiers, since autotrophic ammonia oxidizers never could be detected, and autotrophic nitrite oxidizers were usually not found in appreciable cell numbers. The developed MPN method is based on the demonstration of the presence/absence of nitrite/nitrate produced by heterotrophic nitrifying bacteria during growth in a complex medium (peptone-meat-extract softagar medium) containing low concentrations of agar (0.1 per cent). Both the supply of the growing cultures in MPN test tubes with sufficient oxygen and the presence of low agar concentrations in the medium were found to be favourable for sustainable nitrite/nitrate production. The results demonstrate that in the acidic forest soil the microbial population capable of heterotrophic nitrification represents a significant part of the total aerobic heterotrophic population. By applying the developed MPN method, several bacterial strains of different genera not previously described to perform heterotrophic nitrification have been isolated from the soil and have been identified by bacterio-diagnostic tests.
  • Publication
    Influence of acid rain and liming on fluxes of NO and NO2 from forest soil
    ( 1998)
    Papke, H.
    ;
    Papen, H.
    Flux measurements of nitric oxide (NO) and nitrogen dioxide (N02) were performed in a coniferous forest (Höglwald) in southern Germany using a fully automated measuring system based on the dynamic chamber method. The forest soil was predominately a source of NO, but mean flux rates of NO ranged from -26.3 (deposition) to 55 my g N m(-2) h(- 1) (emission). NO2 was deposited on the forest soil with mean flux rates ranging from -4 to -72 my g N m(-2) h(-1) . Removal of forest floor vegetation did not influence NO or NO2 fluxes. Apparently, forest floor vegetation was neither a source of NO nor a significant sink of NO2. When the organic layer of the forest soil was removed, net NO flux changed from emission to deposition. Thus NO emitted to the atmosphere was produced almost exclusively in the organic layer of the forest soil. Liming caused a significant decrease in the rate of NO emission by 43 to 100 per cent, whereas irrigation with simulated acid rain increased the emission of NO by a factor of 3. 1. Irrigation with simulated "normal" rain decreased the emission of NO by 35 to 100 per cent. No such effects could be detected for the deposition of NO2.
  • Publication
    Exchange of NO and NO2 between wheat canopy monoliths and the atmosphere
    ( 1996)
    Weber, P.
    ;
    Rennenberg, H.
    The fluxes of NO and NO2 between wheat canopy monoliths and the atmosphere were investigated with the dynamic chamber technique. For this purpose monoliths were dug out at different plant growth stages from a field site, transported to the institute, and placed in an environmental growth chamber. The wheat canopy monoliths were exposed over a period of four days to the average ratios of atmospheric NO2 and NO measured at the field site, i.e. NO2 concentration of about 18 mL L(-1) plus NO concentration lower than 0.5 nL L(-1). Under these conditions NO emission into the atmosphere and NO2 deposition into canopy monoliths was observed. Both fluxes showed diurnal variation with maximum rates during the light and minimum rates during darkness. NO2 fluxes correlated with soil temperature as well as with light intensity. NO fluxes correlated with soil temperature but not with light intensity. From the investigation performed the diurnal variation of the NO and NO2 compensation points, the ma ximum rates of NO and NO2 emission, and the total resistances of NO and NO2 fluxes were calculated. Under the assumption that the measured data are representative for the whole vegetation period, annual fluxes of NO and NO2 were estimated. Annual NO emission into the atmosphere amounted to 87 mg N m(-2) y(-1) (0.87 kg ha(-1) y(-1), annual NO2 deposition into canopy monoliths amounted to 1273 mg N m- 2 y(-1) (12.73 kg ha(-1) y(- 1). Apparently, the uptake of atmospheric nitrogen by the wheat field from NO2 deposition is about 15 times higher than the loss of nitrogen from NO emission. It can therefore be assumed that even in rural areas wheat fields are a considerable sink for atmospheric nitrogen. The annual sink strength estimated in the present study is ca. 12 kg N ha(-1) y(-1). The possible origin of the NO emitted and the fate of atmospheric NO2 taken up by the wheat canopy monoliths are discussed.
  • Publication
    Inhibition of apoplastic and symplastic peroxidase activity from Norway spruce by the photooxidant hydroxymethyl hydroperoxide
    ( 1994)
    Polle, A.
    ;
    Junkermann, W.
    Young, clonal Norway spruce trees (Picea abies L.) were exposed for 2 years at high altitudes to ambient atmospheric concentrations of photooxidants containing hydroxymethyl hydroperoxide (HMHP) as an important constituent. In spruce needles from a site with higher concentrations of organic peroxides in air, the apoplastic peroxidase activities were significantly lower than in needles exposed to lower organic peroxide concentrations. Guaiacol peroxidase activities in total needle extracts were not affected. In vitro HMHP at a concentration of 35 myM inhibited apoplastic and total needle guaiacol peroxidase activities by 50 per cent at pH 5.25. At the same pH, ascorbate-specific peroxidase activity required about 100 myM HMHP for 50 per cnet inhibition. At pH 7,1.46 mm HMHP caused a 50 per cent reduction in guaiacol peroxidase and a 13 per cent reduction in ascorbate peroxidase activity. The present results suggest that HMHP in ambient air may affect peroxidase activity in spruce needle s. Peroxidases located in the relatively acidic aqueous phase of the cell walls appear to be more susceptible to HMHP inhibition than those present in neutral or slightly alkaline symplastic compartments of cells such as the cytosol or chloroplasts.
  • Publication
    Apoplastic peroxidases and lignification in needles of Norway spruce (Picea abies)
    ( 1994)
    Polle, A.
    ;
    Otter, T.
    ;
    Seifert, F.
    The objective of the present study was to investigate the correlation of soluble apoplastic peroxidase activity with lignification in needles of field-grown Norway spruce (Picea abies L.) trees. Apoplastic peroxidases (EC 1.11.1.7) were obtained by vacuum infiltration of needles. The lignin content of isolated cell walls was determined by the acetyl bromide method. Accumulation of lignin and seasonal variations of apoplastic peroxidase activities were studied in the first year of needle development. The major phase of lignification started after bud break and was terminated about 4 weeks later. This phase correlated with a transient increase in apoplastic guaiacol and coniferyl alcohol peroxidase activity. NADH oxidase activity, which is thought to sustain peroxidase activity by production of H2O2, peaked sharply after bud break and decreased during the lignification period. Histochemical localization of peroxidase with guaiacol indicated that high activities were present in lignifying cell walls. In mature needles, lignin was localized in walls of most needle tissues including mesophyll cells, and corresponded to 80 to 130 my mol lignin monomers/g needle dry weight. Isoelectric focusing of apoplastic washing fluids and activity staining with guaiacol showed the presence of strongly alkaline peroxidases (isoelectric point >= 9) in all developmental stages investigated. New isozymes with isoelectric points of 7.1 and 8.1 appeared during the major phase of lignification. These isozymes disappeared after lignification was terminated. A strong increase in peroxidase activity in autumn was associated with the appearance of acidic peroxidases (isoelectric point <= 3). These results suggest that soluble alkaline apoplastic peroxidases participate in lignin formation. Soluble acidic apoplastic peroxidases were apparently unrelated to developmentally regulated lignification in spruce needles.
  • Publication
    The antioxidative system in manganese-deficient spruce needles (Picea abies, L.)
    ( 1992)
    Polle, A.
    ;
    Chakrabarti, K.
    ;
    Chakrabarti, S.
    ;
    Seifert, G.
    ;
    Schrammel, P.
    ;
    Rennenberg, H.